1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
2 | /* |
3 | * Copyright (C) 2011-2017 Red Hat, Inc. |
4 | * |
5 | * This file is released under the GPL. |
6 | */ |
7 | |
8 | #ifndef DM_BIO_PRISON_V2_H |
9 | #define DM_BIO_PRISON_V2_H |
10 | |
11 | #include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */ |
12 | #include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */ |
13 | |
14 | #include <linux/bio.h> |
15 | #include <linux/rbtree.h> |
16 | #include <linux/workqueue.h> |
17 | |
18 | /*----------------------------------------------------------------*/ |
19 | |
20 | int dm_bio_prison_init_v2(void); |
21 | void dm_bio_prison_exit_v2(void); |
22 | |
23 | /* |
24 | * Sometimes we can't deal with a bio straight away. We put them in prison |
25 | * where they can't cause any mischief. Bios are put in a cell identified |
26 | * by a key, multiple bios can be in the same cell. When the cell is |
27 | * subsequently unlocked the bios become available. |
28 | */ |
29 | struct dm_bio_prison_v2; |
30 | |
31 | /* |
32 | * Keys define a range of blocks within either a virtual or physical |
33 | * device. |
34 | */ |
35 | struct dm_cell_key_v2 { |
36 | int virtual; |
37 | dm_thin_id dev; |
38 | dm_block_t block_begin, block_end; |
39 | }; |
40 | |
41 | /* |
42 | * Treat this as opaque, only in header so callers can manage allocation |
43 | * themselves. |
44 | */ |
45 | struct dm_bio_prison_cell_v2 { |
46 | // FIXME: pack these |
47 | bool exclusive_lock; |
48 | unsigned int exclusive_level; |
49 | unsigned int shared_count; |
50 | struct work_struct *quiesce_continuation; |
51 | |
52 | struct rb_node node; |
53 | struct dm_cell_key_v2 key; |
54 | struct bio_list bios; |
55 | }; |
56 | |
57 | struct dm_bio_prison_v2 *dm_bio_prison_create_v2(struct workqueue_struct *wq); |
58 | void dm_bio_prison_destroy_v2(struct dm_bio_prison_v2 *prison); |
59 | |
60 | /* |
61 | * These two functions just wrap a mempool. This is a transitory step: |
62 | * Eventually all bio prison clients should manage their own cell memory. |
63 | * |
64 | * Like mempool_alloc(), dm_bio_prison_alloc_cell_v2() can only fail if called |
65 | * in interrupt context or passed GFP_NOWAIT. |
66 | */ |
67 | struct dm_bio_prison_cell_v2 *dm_bio_prison_alloc_cell_v2(struct dm_bio_prison_v2 *prison, |
68 | gfp_t gfp); |
69 | void dm_bio_prison_free_cell_v2(struct dm_bio_prison_v2 *prison, |
70 | struct dm_bio_prison_cell_v2 *cell); |
71 | |
72 | /* |
73 | * Shared locks have a bio associated with them. |
74 | * |
75 | * If the lock is granted the caller can continue to use the bio, and must |
76 | * call dm_cell_put_v2() to drop the reference count when finished using it. |
77 | * |
78 | * If the lock cannot be granted then the bio will be tracked within the |
79 | * cell, and later given to the holder of the exclusive lock. |
80 | * |
81 | * See dm_cell_lock_v2() for discussion of the lock_level parameter. |
82 | * |
83 | * Compare *cell_result with cell_prealloc to see if the prealloc was used. |
84 | * If cell_prealloc was used then inmate wasn't added to it. |
85 | * |
86 | * Returns true if the lock is granted. |
87 | */ |
88 | bool dm_cell_get_v2(struct dm_bio_prison_v2 *prison, |
89 | struct dm_cell_key_v2 *key, |
90 | unsigned int lock_level, |
91 | struct bio *inmate, |
92 | struct dm_bio_prison_cell_v2 *cell_prealloc, |
93 | struct dm_bio_prison_cell_v2 **cell_result); |
94 | |
95 | /* |
96 | * Decrement the shared reference count for the lock. Returns true if |
97 | * returning ownership of the cell (ie. you should free it). |
98 | */ |
99 | bool dm_cell_put_v2(struct dm_bio_prison_v2 *prison, |
100 | struct dm_bio_prison_cell_v2 *cell); |
101 | |
102 | /* |
103 | * Locks a cell. No associated bio. Exclusive locks get priority. These |
104 | * locks constrain whether the io locks are granted according to level. |
105 | * |
106 | * Shared locks will still be granted if the lock_level is > (not = to) the |
107 | * exclusive lock level. |
108 | * |
109 | * If an _exclusive_ lock is already held then -EBUSY is returned. |
110 | * |
111 | * Return values: |
112 | * < 0 - error |
113 | * 0 - locked; no quiescing needed |
114 | * 1 - locked; quiescing needed |
115 | */ |
116 | int dm_cell_lock_v2(struct dm_bio_prison_v2 *prison, |
117 | struct dm_cell_key_v2 *key, |
118 | unsigned int lock_level, |
119 | struct dm_bio_prison_cell_v2 *cell_prealloc, |
120 | struct dm_bio_prison_cell_v2 **cell_result); |
121 | |
122 | void dm_cell_quiesce_v2(struct dm_bio_prison_v2 *prison, |
123 | struct dm_bio_prison_cell_v2 *cell, |
124 | struct work_struct *continuation); |
125 | |
126 | /* |
127 | * Promotes an _exclusive_ lock to a higher lock level. |
128 | * |
129 | * Return values: |
130 | * < 0 - error |
131 | * 0 - promoted; no quiescing needed |
132 | * 1 - promoted; quiescing needed |
133 | */ |
134 | int dm_cell_lock_promote_v2(struct dm_bio_prison_v2 *prison, |
135 | struct dm_bio_prison_cell_v2 *cell, |
136 | unsigned int new_lock_level); |
137 | |
138 | /* |
139 | * Adds any held bios to the bio list. |
140 | * |
141 | * There may be shared locks still held at this point even if you quiesced |
142 | * (ie. different lock levels). |
143 | * |
144 | * Returns true if returning ownership of the cell (ie. you should free |
145 | * it). |
146 | */ |
147 | bool dm_cell_unlock_v2(struct dm_bio_prison_v2 *prison, |
148 | struct dm_bio_prison_cell_v2 *cell, |
149 | struct bio_list *bios); |
150 | |
151 | /*----------------------------------------------------------------*/ |
152 | |
153 | #endif |
154 | |